On Saturday at the World Science Festival, microbiologists David Relman, Jo Handelsman, Rob Knight, and Martin Blaser convened for a discussion on how the microbiome relates to our health. Our microbiome, the collective bacteria, viruses, fungi and other microorganisms that live in the digestive tract, allows us to digest food properly and fight off disease. Research suggests that an unhappy microbiome may contribute to autoimmune diseases, allergies, depression, and even Alzheimer’s.

From the time you are born, millions of bacteria from your mother, food, air, the family dog, and everything you touch start setting up camp in your body. In fact, these trillions of microbial partners—symbionts—outnumber our own cells by as many as 10 to one. The environment where these microorganisms reside is known as the microbiome, and most live in your colon, where they help signal your body to digest food, fight pathogens, break cholesterol down, and more.

The microbiome is the focus of July’s Cerebrum feature (posting on July 1): “Gut Feelings: Bacteria and the Brain.” Authored by Jane Foster, Ph.D., an associate professor in the Department of
Credit: Sebastian Kaulitzki/shutterstock.comPsychiatry and Behavioral Neurosciences at the Brain-Body Institute at McMaster University in Canada, her story focuses on animal studies that have shown microbiota to be instrumental in how our brain develops. The gut-brain axis— sometimes referred to as the “second genome” or the “second brain”— could have implications in how we behave, react to stress, and respond to treatment for depression and anxiety.

Among the most exciting new frontiers in neuroscience, the microbiome is better known for its relationship to probiotics, the so-called “good bacteria” that has been synthesized in pill or capsule form or used in food products such as yogurt, dark chocolate, soft cheese, pickles, and more. Commonly found next to the vitamin supplements on supermarket or drugstore shelves, probiotics claim to support immunity and fix everything from bloat to skin trouble to digestive problems, and sales of anything having to do with “good bacteria” supplements have increased by $1 billion in the United States in the last two years alone.